CAFFEINE CONTENT IN COFFEE AS INFLUENCED BY GRINDING AND BREWING TECHNIQUES

The caffeine content of coffee as influenced by various coffee prepara tion methods was investigated. The variables studied included the coff ee solids to water volume ratio, the volume of coffee prepared, home v ersus store grinding, and drip/filtered versus boiling. Caffeine conte nts per 177 ml (6 oz) of coffee ranged from 50 to 143 mg, depending up on the mode of preparation. As expected, more coffee solids and larger extents of grinding led to significantly higher caffeine contents in filtered coffee. Larger volumes of coffee prepared at a constant coffe e solids to water ratio also yielded significantly higher caffeine con tents. Home-grinding yielded caffeine contents similar to that of stor e-ground coffee. Boiled coffee had caffeine contents equal to or great er than filtered coffee, depending upon the length of boiling time. Th e variable caffeine contents in coffee resulting from the mode of prep aration should be recognized and addressed by both food composition da ta bases and epidemiologists. (C) 1997 Published by Elsevier Science L td on behalf of the Canadian Institute of Food Science and Technology.